Front rotors removal... (1 Viewer)

[IdahoDoug]

Not to rain on your parade, but many have had their rotors turned (which makes them MORE prone to warp) only to have the rotors warp again quickly. I foolishly went against my own policy never to turn rotors, and mine lasted exactly 42 days before warping again. The work to pull them, clean the wheel bearings and reassemble them seems to merit spending $200 or less (minus the turning fee, BTW) for new rotors and slapping them on. Let us know how your experience is if you could.

Doug

 

[sjcruiser]

Doug,

Good point. I'd never pay anyone only to make my rotors thinner. The exception here is due to the fact that they are only a year old. I'm trying to save it first but if this does not work out, I'll bite the bullet & feed Dan's chubby dogs \


Frank.

 

[cruiserdan]

Chubby?

These are bird dogs, no chubby here. Now the owner..........

 

[sjcruiser]

Repacked the front bearings along with the turned rotors (~31mm thickness) Friday night. Took it out for a ride - God I had missed that smoothe brake pedal feel since the truck rolled off the dealer lot. Now just keep my fingers crossed on how long it's gonna last

Tim, how about yours ?

Frank.

 

[concretejungle]

I know i'm going to take beating for this but what is a FSM? Factory Service Manual i'm assuming. Can i get one at the local dealer? Reason i'm asking is i just turned my rotors and repacked my bearings last weekend. Just used the post on 80scool, and a haynes repair manual. Basically just put everything back the way it came off. Everything went well, except went through pile of towels and ruined clothes with grease.

 

[waldrtw]

Well,

I too spent Friday night packing the bearings and putting it back together. It went together alot faster than it came apart!! Took mine out for a spin Sat and it drove great!!! I just hope they do not warp again like some of you say. I guess if I have to do it again I should be real quick at it. I believe the reason for my rotors to be warped was the drive a made from Wilmington NC to Portland Oregon I made this summer pulling a loaded down U-haul trailor. I learned to always check your brakes before going on a 3000 mile trip!!!!

Tim

 

[Beowulf]

There is a good link in a post in the archives discussing the warped rotor myth. That's the term used by the author of the article who makes a good case that the brake pulsing is not really warped rotors and that, in his experience, very very few rotors are warped.

The "Warped" Brake Disc and Other Myths of the Braking System

Please read the above article but if you don't do anything else, use his recommended procedure for bedding the new brake pads to the new rotors.


(Later... some people don't have the capability at work to follow other links. Here is the bedding procedure)

PREVENTION

There is only one way to prevent this sort of thing - following proper break in procedures for both pad and disc and use the correct pad for your driving style and conditions. All high performance after market discs and pads should come with both installation and break in instructions. The procedures are very similar between manufacturers. With respect to the pads, the bonding resins must be burned off relatively slowly to avoid both fade and uneven deposits. The procedure is several stops of increasing severity with a brief cooling period between them. After the last stop, the system should be allowed to cool to ambient temperature. Typically, a series of ten increasingly hard stops from 60mph to 5 mph with normal acceleration in between should get the job done for a high performance street pad. During pad or disc break-in, do not come to a complete stop, so plan where and when you do this procedure with care and concern for yourself and the safety of others. If you come to a complete stop before the break-in process is completed there is the chance for non-uniform pad material transfer or pad imprinting to take place and the results will be what the whole process is trying to avoid. Game over.

In terms of stop severity, an ABS active stop would typically be around 0.9 G’s and above, depending on the vehicle. What you want to do is stop at a rate around 0.7

to 0.9 G's. That is a deceleration rate near but below lock up or ABS intervention. You should begin to smell pads at the 5th to 7th stop and the smell should diminish before the last stop. A powdery gray area will become visible on the edge of the pad (actually the edge of the friction material in contact with the disc - not the backing plate) where the paint and resins of the pad are burning off. When the gray area on the edges of the pads are about 1/8" deep, the pad is bedded.

-B-

 

[e9999]

well, just had a dealer measure the rotors on this 100 my wife wanted to buy. He measured 8 thous of runout in the front. Does this qualify as warped or do you think this is also deposits?
[ed: just saw the author above mentioning 1 thou of deposits as notably annoying already, so I'm guessing that was really warpage...]
E

 

[IdahoDoug]

Beo,

Interesting stuff. I did an internet search and found some references to cementite on the Brembo website, and a bunch that came from various Yahoo discussion groups. No real scientific discussions of it as a side effect of overheating a brake rotor with use, but some references to it as a part of manufacturing them. I'm curious why a term "cementite" that's frequently mentioned by two companies who sell brakes (Brembo and Stoptech) isn't commonly discussed elsewhere.

The Brembo site was an impressive array of general braking information, I will say. The Stoptech article kinda stuck in my craw when he categorically stated he'd never seen a warped rotor. You know what I mean? I have not spent a lifetime in the brake industry but can absolutely state that my 80s brake rotors were warped. They were turned by a personal friend at his shop and I watched him measure the runout, then also watched as he lovingly adjusted the machine to take off just exactly what was needed to cause the rotors to run true without any lateral movement. This took extra care, where at a normal shop they'll just take a lot of material off quickly to move on rather than carefully adjust for each rotor's warpage.

Could the material surface variations be buildup, rather than warpage? No. The material variation began at the inner radius of the rotor's friction surface (where there is no pad contact), and continued radially outward across the pad's contact area. In addition, the movement of the entire edge of the rotor back and forth indicated the actual rotor's edge was moving - it was not getting thicker and thinner. This is not the first time I've personally seen this, so I detect a bit of BS.

I find the comments about breakin of pads extremely helpful and will never again put pads on without doing this. I suspect the Stoptech author is correct about hard spots developing from local hot spots, but kind of overstated his case a bit. No harm done, but I still believe in warped rotors.

Doug

 

[cruiserdan]

I like warped rotors too $$$=dog food

 

[waldrtw]

I read the piece about the brake warpage and I have to say he made some good points but I still believe that brakes can warp. Just like some of you mentioned I too Saw the runout on my brake rotors. I guess if I do it again I will take them to the shop next door to me and have them put in a Cryogenic Chamber to reconstruct the Carbon structure in the metal. Let me know if any of you would like this done so some pieces of you rig. I assume everybody is aware of Cryogenics?


Tim

 

[sjcruiser]

Tim,

My front rotors are cryogenized (ordered from www.frozenrotors.com). Had a shop put them on a year ago, but it soon warped afterward; hope that the mechanics had just over torqued them. Now feeling assured that the job is done properly (by me ) I'd see how long these rotors last.


Frank.